The present invention relates to a method and apparatus for investigating the properties of seabeds.
When assessing a sub-sea location for its suitability for oil production, it is important to consider the characteristics of the soil. The type of soil will affect the drilling of the well and the construction of the platform in a profound way. The characteristics of the seabed soils must also be considered in the design, construction and operation of structures found on the seabed, and other construction work, such a laying oil pipes, cables, anchorages and the like. It could even be used for general prospecting and surveying.
A known systems for gathering data involve drilling a borehole in a conventional way, removing the drill string, and then lowering soil analysis equipment into the borehole. It is time consuming and difficult, not merely to remove the drill string but to introduce the soil analysis equipment into the borehole, especially where the location is in deep water. This necessitates the guidance of the soil analysis equipment into the borehole, which is complicated by the swell of the sea, which causes the vessel to rise and fall relative to the seabed.
GB 2 243 173 A discloses a method of reducing this delay and difficulty. After having removed the drill string and drill bit, the drill bit is taken off the drill string, and the soil analysis equipment put on in its place. The solid analysis equipment is then lowered into the borehole upon the drill string. This method is suitable for land, but guiding the drill string back into the borehole is not such an easy matter at sea.
The object of the present invention is to provide an apparatus for investigating soil beneath the seabed in an efficient manner.
According to the present invention there is provided a method for deploying test equipment from a floating vessel or the like, the test equipment comprising testing apparatus for determining geotechnical, geophysical, geochemical, geological characteristics, and soil penetration means which forms an exploratory hole, the testing apparatus including at least one sensor or sampling means, the test equipment being deployed by coiled tubing or the like, the one end of the coiled tubing being attached to the vessel.
Preferably the test equipment is of sufficient weight to keep itself and the coiled tubing above it substantially vertical.
Preferably the test equipment is kept correctly orientated by a structure resting substantially on the seabed.
According to another aspect of the present invention, there is provided test equipment as defined above.
Methods of testing the soil characteristics will vary for the soil type and application. Testing is intended to encompass such areas as geotechnical, geophysical, geochemical, geological testing. It is also intended to cover methods such as the use of simulators, that is miniature versions of equipment which may be developed in or on the seabed.